(1) Field of the Invention
The present invention relates to a method of operating a numerical control (NC) machine tool in accordance with workpiece and tool profiling data in order to fabricate a product.
(2) Description of the Prior Art
In numerical control (NC) machine tools, data for the desired positions of the tool is fed from an NC tape into the NC machine to control tool movement and position.
However, disadvantages arise when, for example, a metal mold having a three dimensional profile is fabricated using such an NC machine tool. Then preparation of the NC tape is difficult, especially if the three-dimensional profile of the metal mold includes curved surfaces which cannot be expressed mathematically, and the NC tape can become very lengthy as the curved surfaces become more complicated.
On the other hand, a profiling lathe may be used wherein a stylus travels along the surface of a previously prepared physical model, and a tool is moved along the surface of the workpiece in a manner coordinated with the motion of the stylus by means of a feed mechanism, so that the surface profile of the finished workpiece will conform completely to that of the model. Therefore, if the profiled model has a complicated three-dimensional profile, such a profile lathe can complete the precise profiling of the work relatively easily. However, it takes a considerably long time to prepare a highly precise model for profiling, and the wear of the stylus results in deterioration of precision of the profiled model due to the repeated use of the same profiled model and stylus.
In this way, there have been problems in these two methods of providing positional data in these two kinds of machine tools.